1. Field of the Invention
This invention relates to a numerically controlling apparatus for a machine tool comprising the function of automatically determining tools and machining conditions and the function of displaying and editing tool paths. (Hereinafter, terms concerning numerical control such as "numerically controlling", "numerically controlled", of course "numerical control" itself, and so forth are collectively denoted by "NC" for short.)
2. Description of the Prior Art
FIG. 1 illustrates a summarized block diagram of a conventional NC apparatus for the machine tool shown in, for example, Japanese Unexamined Patent Applications Published under No. 188249/89 (Hei. 1), No. 138504/92 (Hei. 4), No. 234135/89 (Hei. 1), No. 122524/92 (Hei. 4), and the like. In FIG. 1, reference numeral 201 designates a tool and machining condition data memorizing means, reference numeral 4 designates a working process information inputting means, reference numeral 5 designates a tools and machining conditions automatically determining means, reference numeral 6 designates an NC data generating means, and reference numeral 7 designates an NC device.
Next, the operation will be described thereof. When an operator uses the NC apparatus for a machine tool constructed as mentioned above, he inputs such data as material forms, working forms and so on into the apparatus, and divides each working region into working processes, and further makes up working process information in conformity with the procedures of the making up operations of NC programs. For instance, when he practices lathe working, he divides each working region capable of being worked with one tool (such as the working region of outside diameter turning, the working region of end face turning, the working region of inside diameter turning and the like) into working processes, then he gives working process information such as the kinds of working (or outside diameter cutting, end face cutting, etc.), the kinds of work materials (or cast iron, aluminum, etc.) and so on to each of those working processes. The working process information is made up to each working process. Then, according to the inputted working information, the NC apparatus for the machine tool automatically determines tools and machining conditions suitable for each working process on the basis of the data memorized in the tool and machining condition data memorizing means 201. For example, supposing that the working form is a hole having the diameter of 10 mm, a drill having the diameter of 10 mm is determined as the suitable tool to be used, and a machining condition to this work material is called out among the registered machining conditions as those for the drill being 10 mm in diameter as the suitable machining condition.
FIG. 2 illustrates a summarized block diagram of a conventional NC apparatus for the machine tool (or an electric discharge machine) shown in, for example, Japanese Unexamined Patent Applications Published under No. 130130/87 (Sho. 62), No. 130131/87 (Sho. 62), No. 307051/87 (Sho. 62), No. 38631/93 (Hei. 5), and the like. In FIG. 2, reference numeral 211 designates a machining condition generator in electric discharge working, reference numeral 216 designates an electric discharge machine, reference numeral 217 designates a power source, and reference numeral 218 designates an NC device driving and controlling the electric discharge machine 216 in conformity with the machining conditions set by the machining condition generator 211. Moreover, reference numeral 212 designates an input part receiving demanded specifications by a user, reference numeral 214 designates a machining condition generation part generating machining conditions from the inputted demanded specifications, reference numeral 215 designates a machining condition holding means for holding memories of machining conditions necessary to generate machining conditions, and reference numeral 213 designates an output part outputting generated machining conditions.
Next, the operation will be described thereof. When a user uses the NC apparatus for the machine tool constructed as mentioned above, he inputs the demanded specifications from a.sub.1 to a.sub.n such as the working base area a.sub.1, working depth a.sub.2, the amounts of decreased electrode length a.sub.3, etc. and the demanded specifications from b.sub.1 to b.sub.3 such as machined surface roughness b.sub.1, the amounts of electrode consumption b.sub.2, working time b.sub.3, etc. into the NC apparatus for the machine tool through the input part 212 on the basis of the specifications required for objects to be worked. The machining condition generation part 214, which received the demanded specifications a.sub.1 to a.sub.n and b.sub.1 to b.sub.3, generates at least one machining condition fitted to the demanded specifications, namely a machining condition train c.sub.1 to c.sub.m composed of electric conditions such as peak current values, pulse widths, pose time, polarities, using current waveforms, etc. at each working step and the amounts of bringing the electrode near to the final working surface (or electrode bringing amounts) etc., then the machining condition generation part 214 sets them into the output part 213. Besides, the output part 213 displays the set data on the cathode-ray tube display (or CRT: not shown), and outputs them to the floppy disk unit (not shown) or the NC device 218. Thereby, the machining conditions in the electric discharge are automatically set.
FIG. 3 illustrates a block diagram of a conventional NC apparatus for the machine tool having the function of displaying the working paths of its tool on the display screen of a display unit on the basis of its NC program. In FIG. 3, reference numeral 81 designates a display unit, reference numeral 82 designates a data entry unit, reference numeral 7 designates an NC device, reference numeral 221 designates NC programs, reference numeral 222 designates an NC programs transforming means, reference numeral 223 designates a correction calculation executing means, reference numeral 224 designates an interpolating means, and reference numeral 225 designates a tool path data displaying means.
Next, the operation will be described thereof. In the NC apparatus for the machine tool constructed as mentioned above, the made up NC programs are transformed into inside data by each of a certain unit (hereinafter referred to as working block) by the NC programs transforming means 222 at first. The incremental movement amounts of each working block are calculated by the correction calculation executing means 223 using the inside data. Moreover, corrections are made using the data such as tool diameters, tool length and the like. The processing of renewing inside coordinate values is also executed. These data are further utilized for operating the movement amounts of each shaft of the NC machine tool at every minute period of time in the interpolating means 224. On the other hand, the tool path data displaying means 225 transforms these data into the coordinate values on the display screen of the display unit 81 to display the transformed coordinate data on the display unit 81 as the working paths of the tool.
Because conventional NC apparatus for machine tools are constructed as mentioned above, they have problems that they require changing the contents of their databases in advance for reflecting the know-how possessed by skillful workers on the automatic determination, since they have respectively only one tool and machining condition data memorizing means, which is the basis of the automatic determination, or even if they have plural memorizing means, each of the memorizing means is a division of one memorizing means in contents, and that if the contents of the databases have been changed in advance, when the automatic determination based on standard data having no know-how is contrarily wanted, it is needed to restore the original data to the databases again.
Furthermore, although the machining conditions are automatically determined, they are determined in conformity with single algorithm, then there is a problem that if there exist working objects or tools not supposed at the beginning, it is impossible to select the optimum machining conditions, in such a case the optimum conditions are sometimes selected by the experiences and the perceptions of skillful workers, but not everybody can do the operations and it is impossible to select the strictly optimum or quasi-optimum machining conditions in this case also.
Furthermore, the conventional NC apparatus for the machine tool display the working paths of their tools on the display screens of their display units, transforming and executing correction processes from the beginning to the end in the order, and consequently, it is possible to recognize the working paths of their tools in conformity with the entire NC programs, but it is impossible that an operator makes them display only a local working path to a certain working region. Moreover, because the conventional NC apparatus for the machine tool do not memorize the displayed working path data of tools and have not means for identifying the correspondences with their NC programs, the operator who wants to modify the displayed working path data of tools or the visible outlines of working regions has to judge which portions of the NC programs the working paths of tools or the visible outlines of working regions wanted to be modified correspond to the working path data, and has to modify the NC programs after that. Consequently the conventional NC apparatus for a machine tool have a problem that the efficiency of the operations of making up NC programs is bad.